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Updated: Apr 2, 2020

Feline Calicivirus or FCV is a common virus in cats that presents with respiratory disease. There are at least 40 strains.


Present in about 10% of cats (either in active or carrier state). In shelters or catteries it is closer to 25 to 40%.


  • Sneezing

  • Congestion

  • Inflammation of the inner eye lids

  • Discharge from nose and eyes either clear or containing pus

  • Can also present ulcers on nose, tongue, lips etc. Lethargy

  • Fever

  • Stop eating

  • Enlarged lymph nodes Pneumonia

  • Lameness

  • Muscle weakness

  • Symptoms vary with strain


Incubation 2-6 days Infection lasts 14-21 days Minimum shedding time after seeming recovery is approximately 2-3 weeks


About 50% of cats are carriers and intermittently shed the virus or never shed it all Carrier mothers can pass this to offspring

HOW: 1. Air via little droplets. Some can fall to the floor others hop a ride on dust and are inhaled by another cat 2. Contaminated Objects such as water bowls, litter boxes, toys, blankets etc. 3. Direct contact with other animals via secretions/discharge like saliva, feces, nasal droplets

Can exist on dry surfaces at room temperature including up to one month after infection


Via with eye, oral swabs, blood, skin scrapings or lung tissue PCR is the one of the best ways to detect however a positive result may be due to low levels of shedding found in carriers or after vaccination



Uncomplicated cases tend to be treated with eye ointments to prevent secondary bacterial infection as well as products for immune support, but generally there is no specific treatment


  • Steam shower once a day for 10-15 minutes

  • Clearing the airways from nasal secretions

  • Amber Technology’s Numo Care C for bronchial support

  • Fluids

  • Oxycat

  • ViraX

  • Antioxidants like krill oil

  • Ozone Therapy

Homeopathic nosode Herbs such as:

  • Aloe vera

  • Astragalus

  • Goldenseal

  • Marshmallow

  • Nettle

  • Reishi Mushrooms

  • Seaweed

  • Shiitake Mushrooms

  • St. John’s Wort

  • Turmeric

  • Yellow Dock

Homeopathic remedy such as:

  • Aconitum napellus 30C

  • Nux vomica 30C

  • Natrum muriaticum 6C, or Pulsatilla 30C followed by Silicea 30C.

If mouth ulcers associated • Nitricum acidum 30C


If depression, dehydration and severe illness progress other supportive care will be needed


Keep things sanitary including the air It is a virus but can form secondary infections so antibiotics will not cure the virusPowerful medical grade UV-C light Clean the home with 1:32 diluted bleach

VACCINATION: Vaccinating for the virus is difficult as this virus easily mutates. It is similar to the flu virus in humans in this sense. The vaccine is only 63.3% efficient. Despite triple vaccination, 36.7% of kittens do not seroconvert.

It is also one of several animal vaccines that can shed for 6 weeks - 1 year after administration and transfer illness to dogs and even humans.

It is one of a few feline vaccines that are commonly grown in Crandall-Reese Feline Kidney ("CRFK") cells. As a consequence, the feline vaccines contain CRFK proteins. A study conducted by Colorado State University showed that only one injection of the common feline three-in-one vaccination (FVRCP) led to the production of anti-kidney antibodies.

This study indicates that vaccination could be a cause for chronic renal failure in cats. The vaccine only lessens severity and duration of illness it does not prevent it.

Despite vaccination many cats are carriers and thus can shed the virus passing it to offspring or other cats

Attenuated vaccine (that have been reduced pathogen virulence) can cause mild URis.

Inactivated vaccines do not but can cause inflammation at the injection site and predisposes the cat to vaccine-associated sarcoma.

That being said, FCV can easily mutate into new strains especially due to environmental pressures so it is hard to develop a truly effective vaccine.

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